section DOM section

Description

Extensions to DOM elements, plus other utilities for DOM traversal
and modification.

Prototype's DOM extensions represent a large portion of where you'll spend
your time. Prototype adds many convenience methods to elements returned by
the $ function. For instance, you can write

$('comments').addClassName('active').show();

to get the element with the ID of comments, add a class name to it, and
show it (if it was previously hidden).

In other words, Prototype adds "instance" methods to DOM nodes. This is
made possible by direct extension of the backing DOM objects (in browsers
that support it) and by manual extension of individual nodes (in browsers
that do not).